$20.49 – Xiaomi Mijia Hygrometer Thermometer Pro (Banggood, Aliexpress: Xiaomi Mijia Smart Temperature Humidity Pro Electronic Digital Clock Watch E-link Thermometer Moisture Meter Work Mi Home (the best price with coupon)).
According to my DB the lowest price is $20.49 for Xiaomi Mijia Hygrometer Thermometer Pro (in Banggood). Price history, coupons and price alert are available on this page. You probably want to know what is the best price?
Latest coupon code price check (UTC time):
Banggood ($20.49)
Banggood warehouse is located in China. There is no active coupon in my database right now (for Banggood). You probably want to know if this is a good price. Hmmm, price is higher than average (which is $16.94 right now), so better set price alert down below…
Link: Banggood product page
Price: $20.49
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/feV
Old coupons (from the oldest to the newest): BG81309f, BGM1TOOLS88, BG05f151, BG20236Tool, BGTOOS729, BG31a67a
(there’s a little possibility that old coupon will work)
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Price history (for all/most countries) for Xiaomi Mijia Hygrometer Thermometer Pro is here. The lowest price was: $15.99.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).